1. Field of the Invention
The present invention relates to a method and an apparatus for painting vehicle bodies successively carried along a painting line with a suitable color paint selected from a variety of color paints.
2. Prior Art
In well-known prior art painting method, a vehicle body is coated in three different steps, i.e. primer coating for corrosion proofing with the use of electrodeposition coating method; surfacer painting for painting an intermediate coat such as gray color on the primer coating layer; and top coating for painting a desired paint on the intermediate coating layer. In top coating, a variety of different color paints (10 to 30 colors,) are applied to the vehicle bodies, which are successively carried along a conveyor and divided into groups according to a color paint to be applied. To this end, the painting apparatus comprises pluralities of parallel paint-transferring lines L1, L2, L3 . . . LN, such as shown in FIG. 6. The number of the paint-transferring lines corresponds to the variety of the color paints applied to vehicle bodies. At one end of the respective paint-transferring lines L1, L2, L3 . . . LN, a paint tank 35 is positioned so as to reserve a paint having a certain viscosity, which is prepared from different color paints to be mixed. Provided at the other end of these lines L1, L2, L3 . . . LN is a paint-changing unit 32 such as disclosed in Japanese Patent No. 1822017. The paint-changing unit 32 is used for in turn selecting a required color paint and transferring the selected color paint to a spray gun G.
In such painting apparatus, there is provided a washing unit C in parallel relation to the paint-transferring lines L1, L2, L3 . . . LN. When changing a color paint to be applied, the washing unit C ejects washing liquid into a connecting hose 33 between the paint-changing unit 32 and the spray gun G, thereby cleaning remaining paint within the hose. New color paint is then supplied to the spray gun G through the connecting hose 33 thus cleaned.